The present invention relates to an electric machine, and in particular to a cooling system for such an electric machine.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Losses occur in electric machines while they are operating that result in heat generation. Heat is generated partially in the stator device and partially in the rotor of the electric machine and has to be ducted away from the electric machine. Cooling the stator device can be realized using air or alternatively a liquid cooling medium, for example water. When electric machines of relatively low protection class is involved, removal of heat from the internal rotor space can be realized fairly easily. In the case of electric machines that are enclosed in accordance with a relatively high protection class—IP 55 or better—the internal rotor space cannot be cooled directly by using outside ambient air. The presence of an internal cooling circuit is therefore provided in which air circulates between the internal rotor space and the stator device. The internal rotor space is cooled indirectly via the stator device.
It would be desirable and advantageous to provide an improved electric machine to obviate prior art shortcomings and to provide efficient cooling of the electric machine while exploiting generated thermal energy produced in particular in the internal rotor space.